Earnshaw SR, Graham CN, Amonkar MM, Barr C. The cost-effectiveness of ibandronate in the treatment of postmenopausal osteoporosis in the US. Poster presented at the 2006 ISPOR 11th Annual International Meeting; May 20, 2006. Philadelphia, PA. [abstract] Value Health. 2006 May; 9(3):A163.

OBJECTIVES: We determined the cost-effectiveness of monthly ibandronate compared to weekly bisphosphonate (BP) treatments for women in the US, age ≥50 years, with prevalent radiologic vertebral deformity and hip BMD T-score ≤-2.5.

METHODS: A Markov model was developed to evaluate the lifetime cost-effectiveness of monthly ibandronate and weekly BPs. Vertebral, hip, and wrist fracture efficacy were assigned a bisphosphonate class effect as estimated by the literature. Persistence with weekly BPs was evaluated at rates reported from observational studies (36% at year 1, 24% for years 2 through 5). Fifty-percent relative improvement in persistence (54% at year 1, 36% for years 2 through 5) among women receiving ibandronate was assumed based on previous improvements in persistence for weekly BPs. Both fracture risk and mortality were allowed to increase as patients aged. Yearly drug costs were referenced to wholesale acquisition costs for each BP. Direct health resource costs for fracture states were estimated from published literature and discounted 3% per annum. All costs were reported in 2004 US$.

RESULTS: More fractures were avoided (vs. no treatment) with monthly ibandronate (94.13 per 1000 women) than with weekly BPs (57.57 per 1000 women), resulting in low lifetime fracture care costs/woman ($6726 and $6918, respectively). Five-year drug costs/patient were $1138 with weekly BPs and $1576 under conditions of improved persistence with monthly ibandronate. The incremental cost per quality-adjusted life year gained (vs. no treatment) was lower with monthly ibandronate ($26,725) compared to weekly BPs ($31,601). Changing assumptions in the model to that of previously published cost-effectiveness models produced similar results, providing external validity for this model.

CONCLUSION: Ibandronate is a cost-effective intervention for the treatment of postmenopausal osteoporosis. Incremental persistence with BP therapy thus improves the benefit realized in patient populations. These benefits include fewer fractures for patients without significant increases in costs to payers.